This blog discusses current weather, weather prediction, climate issues, and other topics

Sunday, January 19, 2014

Cloud Bowl of Eastern Washington

While many of you are thinking about the Superbowl, today let's talk about another bowl: the Cloudbowl of eastern Washington. While a warm, blazing sun is considered the signature condition of eastern Washington by some (see the logo for the TriCities Visitor Bureau below), the truth is that during the middle of the winter the Columbia Basin of eastern Washington is often filled with fog and stratus clouds: a cloud bowl.

To illustrate, here is a MODIS satellite image from mid-day on Saturday. Typical cloud bowl conditions. You can see low clouds in eastern Washington, with fingers westward in the Cascades to the passes. Such cloud bowl conditions are made worse with high pressure over the region. Notice the low clouds in the Willamette Valley and Puget Sound. Two junior bowls.

So that all of you have the proper sympathy with our brethren in eastern Washington here is a WSDOT cam shot Saturday in Richalnd. How many ways can you say dismal? And such low clouds and fog coupled with low temperatures often produces freezing fog on the bridges in the Tri-Cities. Just wonderful.

The National Weather Service forecast for Richland says it all. You won't find this on the Tri-Cities convention bureau website.

The key issue is that the Columbia Basin of eastern Washington is a topographic bowl, with very narrow openings (e.g., the Columbia Gorge, Okanogan) . Cool air can settle into the lower elevations and sit there. With warmer air frequently overhead, the temperature change with height over the Basin is often characterized by an inversion, with temperature increasing with height.

Take a look at the temperatures, dew point and winds with height at Spokane on Saturday morning (below). The right solid line is temperature. 900 hPA is roughly 3000 ft above sea level. You see that temperature increases with height to above 850 hPA (about 5000 ft) and that temperature and dew point are on top of each other near the surface....that suggests saturation and clouds. We knew that already!

A weather forecast for 1 PM on Saturday showing pressure (solid lines) and low level temperatures (shaded, at 925 hPA, around 2500 ft up) shows cold temperatures (while and blue colors) and high pressure over eastern Washington. This makes sense because cold air is dense.

A surface temperature forecast illustrated the cold air in eastern Washington at 2-meters. Dark blue is the coldest. Colder near the Tri-Cities than at the surface in the Cascades!

Moving up to 850 hPa (around 5000 ft), there is warm, southwesterly flow.

Let me end with some interesting cloud statistics. Below you will see a graphical rendition of the cloud cover percentages over Richland and Seattle at various times of the year. The solid lines are the median cloud cover. The dark band shows that between 40% and 60% of the observations are in that range. Light shades, 25th to 75%.

Richland is in clouds more than 90% of the time from roughly Dec. 1 through Feb 1. Not much different than Seattle. And Richland's clouds are the worse type: low or at the surface. But things improve rapidly in February and by April 6st they are down to 50%. Midsummer...down to 3%.

Seattle is no worse in mid-winter, but clouds stick around until early summer, slowly decreasing in time Seattle NEVER hits the 50% mark, but there is an amazingly rapid decline in late June and early July.

Richland cloudiness

Seattle cloudiness

So avoid the Columbia Basin in mid-winter, but starting around March 1st it is a good bet for sun-starved west siders.

PS: I have been inundated with emails from folks wanting to know the forecast for the SuperBowl--including several bookies and odds-makers. If the Seahawks win (as we all know they will) I will talk about it in the next blog. Some research has suggested that the Seahawks do better in bad weather, so a good forecast is worth a lot of $ to some folks.

Seattle Public Schools Math Curriculum Review

As noted in earlier blogs, Seattle Public Schools is now in the process to review and recommend new math curriculum in K-5, a critical issue considering the poor books now in place (Everyday Math). Three finalists will be selected. The question is whether the process will allow parents and others to comment in an effective and convenient way. Potential books must be available in some public libraries and community centers that are open at night or weekends: not just in a few schools or the Stanford center that close at 5 PM on weekdays. Community members who work need after-hour access. And it is very important that online commenting on the books is allowed. A large amount of information about the potential curricula is available online, including extended samples of the material. Excluding online commenting will limit input, something that works against a fair and representative decision.

6 comments:

Nice write up on why towns in eastern Washington rank so low for sun - that stat from Richland is terrible. And here is the thing that makes it even worse. Often when the fog is gone the wind is blowing very hard. Only other note: the Blue Bridge is located between Pasco and Kennewick.

Do the Seattle schools tell the parents the price difference between different curriculum materials? I served on the textbook committee for a CA district and was surprised that we were asked to give our ranked preferences without knowing the relative costs.

Textbook publishers now place much of the content online. Typically, kids get access to the entire book on the web. The publishers' websites are also full of content designed exclusively for the web like short videos, worked examples and extra practice problems.

Were you given temporary passwords to the publishers' sites to evaluate their digital content? I was surprised that we were not.

BTW, I am not as down on Everyday Math as you are. As a parent, school volunteer, and former math major, I found EM an excellent curriculum for kids who "get" math. The more literal and less imaginative kids had a harder time with it, though.

Cliff, I'm surprised to hear you say that Seattle never gets to less than 50% cloud cover. After all the percent-of-possible sunshine is given as 63% (see Weatherbase) for July, with 12 clear days and 9 cloudy days, the rest partly so.

The "Top of Alpental" cam on the Summit at Snoqualmie website illustrates the cloud bowl nicely. It's always interesting to see from the chair when that condition develops - the clouds looks as if they're pouring over the pass.